1. Field of the Invention
The present invention is related to a method of manufacturing a semiconductor device, and in particular, to a method of manufacturing a semiconductor device provided with bump electrodes (protruded electrodes) to be mounted on a wafer level chip size package (W - CSP), a tape carrier package (TCP), a chip on board (COB), and so forth. This application is a counterpart application of Japanese Application Serial Number 68630/2000, filed Mar. 8, 2000, the subject matter of which is incorporated herein by reference.
2. Description of the Related Art
As a structure for mounting a semiconductor IC chip (referred to hereinafter merely as xe2x80x9cchipxe2x80x9d) on a connecting board, a wafer level chip size package, a tape carrier package, a chip on board, and so forth have so far been proposed. With the structure for mounting the semiconductor IC chip, respective semiconductor components formed in the chip are electrically connected with the connecting board via respective bump electrodes. A structure of the respective bump electrodes is formed by respective steps described as follows.
First, as shown in FIG. 6(A), a metal pad 14 is formed on top of an oxide film 12 formed on a semiconductor (Si) wafer (referred to hereinafter merely as xe2x80x9cwaferxe2x80x9d) 10. Further, a surface protection film 16 and an inter-layer insulation film 18 are formed in that order across the surface of the wafer 10. Thereafteer, a thru-hole is opened over the metal pad 14. Subsequently, an undercoat metal layer 20 is formed across the surface of the wafer 10. Further, a rewiring layer 22 is formed so as to cover a region of the undercoat metal layer 20, extending from the thru-hole over the metal pad 14 to a location where a bump electrode 28 as described later on is to be formed.
Subsequently, as shown in FIG. 6(B), a solid photosensitive resin film 24 is stuck onto the surface of the wafer 10. Owing to a reason from the standpoint of carrying out a film-forming process, a face having microscopic asperities instead of a planar face is formed on the surface of the undercoat metal layer 20 to which the solid photosensitive resin film 24 is stuck.
Accordingly, a resin having high adhesion with the undercoat metal layer 20 is adopted for the solid photosensitive resin film 24. Further, after sticking the solid photosensitive resin film 24 to the undercoat metal layer 20, heat and pressure are applied to the solid photosensitive resin film 24, thereby causing the solid photosensitive resin film 24 to adhere to the surfaces of the undercoat metal layer 20, and rewiring layer 22: Thereafter, the solid photosensitive resin film 24 is subjected to exposure and development, thereby forming an opening 26 for forming the bump electrode. In a next step, the bump electrode 28 made of a metal such as solder (Pbxe2x80x94Sb alloy), or the like is formed inside the opening 26 for forming the bump electrode. Then, as shown in FIG. 6(C), remaining portions of the solid photosensitive resin film 24 are removed, and further, portions of the undercoat metal layer 20, not covered by the wiring layer 22, are removed, thereby forming a structure of the bump electrode 28.
According to the conventional technology described above, however, the solid photosensitive resin film 24 is caused to adhere to the surface of the undercoat metal layer 20 as shown in FIG. 6(B). At this point in time, the solid photosensitive resin film 24 is stuck to the face having the microscopic asperities as well, formed on the surface of the undercoat metal layer 20. In particular, it is hard to remove portions of the solid photosensitive resin film 24, stuck to depressed parts of the face.
Furthermore, as described above, since a constituent material having high adhesion with the undercoat metal layer 20 is adopted for the solid photosensitive resin film 24, there occur cases where the portions of the solid photosensitive resin film 24, stuck to the depressed parts of the face of the undercoat metal layer 20, are left intact even after carrying out removal of the solid photosensitive resin film 24.
Accordingly, it has been highly hoped that unwanted portions of the undercoat metal layer 20 is removed with ease, so that faulty insulation due to presence of remaining portions of the undercoat metal layer 20 can be prevented, resulting in enhanced reliability of a semiconductor device.
It is therefore an object of the invention to provide a method of manufacturing a semiconductor device, whereby occurrence of faulty insulation can be checked, resulting, in enhancement of reliability of the semiconductor device.
To this end, a method of manufacturing a semiconductor device according to one embodiment of the invention comprises forming an electrode pad on top of an insulation film formed on a semiconductor substrate, forming an undercoat electrically conductive layer electrically connected with the electrode pad on top of the insulation film and the electrode pad, forming a wiring layer for electrically connecting the electrode pad with an bump electrode via the undercoat electrically conductive layer over a region of the undercoat electrically conductive layer, extending from a portion thereof, over the electrode pad, to a portion thereof, at a location where the bump electrode is to be formed, forming a first photosensitive resin film on top of the undercoat electrically conductive layer and the wiring layer, forming a second photosensitive resin film on top of the first photosensitive resin film, subjecting the first photosensitive resin film a and the second photosensitive resin film to exposure and development, and forming an opening for forming the bump electrode in a portion of the wiring layer, at the location where the bump electrode is to be formed, so as to expose the portion of the wiring layer, forming the bump electrode electrically connected with the wiring layer inside the opening for forming the bump electrode, removing the first photosensitive resin film and the second photosensitive resin film after the formation of the bump electrode, and removing portions of the undercoat electrically conductive layer, not covered by the wiring layer, after the removal of the f first photosensitive resin film and the second photosensitive resin film, wherein the first photosensitive resin film and the second photosensitive resin film are made of a resin having negative photosensitive property, respectively, and the first photosensitive resin film is made of the resin having weaker adhesion with the undercoat electrically conductive layer than that of the resin for the second photosensitive resin film.